Rakovanite

rakovanite

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Formula: (NH4)3Na3[V10O28].12H2O
Decavanadate, pascoite group
Crystal System: Monoclinic
Specific gravity: 2.407 calculated for the ideal formula, 2.409 for the empirical formula
Hardness: 1
Streak: Orange-yellow
Colour: Orange
Luminescence: No fluorescence under long wave or short wave UV
Environments

Sedimentary environments
Hydrothermal environments

Localities

There are two co-type localities, the Sunday Mine and the West Sunday Mine, both in Slick Rock Mining District, San Miguel County, Colorado, USA. Rakovanite was found on specimens from both mines. The mines are interconnected, and it is likely that these rakovanite samples are not isolated occurrences in the mining complex.
The best crystals were found perched on an amorphous dehydrated vanadium phase along with crystals tightly adhered to a corvusitemontroseite matrix. Associated minerals include calcite, corvusite, hewettite, hughesite, montroseite, munirite, paramontroseite, pascoite, rossite, sherwoodite and other unidentified vanadium phases, as well as at least two other potentially new decavanadate species. Uranium mineralisation occurs predominantly as primary uraninite and coffinite along with minor secondary carnotite.
Rakovanite occurs as crystalline crusts on sandstone fractures in the mine walls. The mineral forms from the oxidation of montroseitecorvusite assemblages.
Crystals of rakovanite are up to 1 mm in maximum dimension and vary in habit from blocky to prismatic, commonly exhibiting steps and striations (CM 49.595-604).

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